The present invention relates generally to an analysis system for use with an electrical utility power system, and more particularly to a system and a method for detecting arcing events on the power system.
Arcing events may be caused by, for example, downed, broken, tangled or dangling power lines, failing hardware on the power system, trees contacting the power lines, and various other fault situations.
Arcing events are more difficult to detect than conventional overcurrent events, which for instance, occur when a transformer or other apparatus fails. Most conventional overcurrent protection devices, such as fuses, reclosers, relays, and the like have time delays that prevent them from detecting a temporary event. Only if an overcurrent event persists does such a device detect the event. Some arcing events may initialize the timing circuits of the overcurrent protection devices but, by the end of the time delay, the impedance of the event limits the event current to a low value. Such overcurrent protection devices cannot distinguish a current from an arcing event from the levels of current ordinarily drawn by customers. Therefore, these devices may not be able to detect arcing events, which may indicate a hazardous condition on the system or the early stages of failure of system apparatus.
Conventional systems for detecting arcing events utilize analysis of a particular parameter of the electrical power system, such as one or more particular frequency components of current or voltage. In such a system, if the current exceeds a particular threshold for a predetermined duration of time or number of occurrences within a predetermined period of time then an arcing-event-detection signal is generated. In another arcing-event-detection system, transients on a transmission line are modeled before, during, and after the fault occurrence using differential equations. Typically, known arcing-event-detection systems utilize one or more frequency components or traveling waves of a property of the electrical power system.
A problem with some conventional arcing-event-detection systems is that they can not detect arcing events that produce difficult-to-measure, low-magnitude currents from arcing events. Low-magnitude currents can be associated with an arcing event when the conductive path to ground has high impedance. Another problem with conventional arcing-event-detection systems is that they can not utilize more than one property of the electrical power system directly to detect arcing events.